Amongst the many types of equipment for photography, the most widely used is the camera. For majority of the general publics, a camera is usually regarded as a recording device during journeys to capture traveling photos such as scenery and their portraits at the site.
As the relevant electronic technology has taken off rapidly and the purchase power has on average increased recently, not only has the camera itself changed its way of recording light from use of chemicals to digital elements, its own functions have also advanced continually in both quantity and quality. Close-up photography that was once classified as a professional skill has become popularized. At present there are numerous consumable cameras, especially digital cameras, capable of close-up photography.
Nevertheless, when performing close-up photography, the camera lens is in close proximity to the object. This leads to a situation in which the surrounding light projecting towards the object becomes blocked by the approaching camera and lens. As a result, the reflected light from the object is inadequate. In order to overcome the problem of inadequate light, the following solutions have been wildly applied.
Firstly, in order to achieve a sufficient exposure value, the shutter opening time is lengthened. This solution is the so-called slow-motion camera shutter, which allows enough light to project to the light recording device, such as the charge-coupled device (CCD), the complementary metal-oxide semiconductor (CMOS) and the negative films. However, the adverse effect of lengthening shutter opening time is an increase in the possibility of camera shock, wasting both the negative films and power.
The second solution is to increase the aperture of the diaphragm. The advantage associated is that it allows more light passing through the lens to reach the light recording device without changing the shutter speed. However, the problem incurred with a greater aperture of the diaphragm is the poorer resolution and contrast of lens. Furthermore, the most serious problem is that the depth of field (DOF) is very narrow when performing close-up photography with a wide-open diaphragm. If using thickness as an analogy, the DOF is often as thin as a piece of paper, i.e. only within the thickness of a paper is the image of the object clear. Anything outside this DOF is blurred. This is obviously an annoyance to users. For example, when wishing to photograph a flower that is a 3D object, the distance from the flower bud, pedal to stem is usually a few tens of millimeters, which is always beyond the coverage of lens with wide-open diaphragm.
Therefore, from the principle of exposure, in order to capture the same exposure value, the shutter is adjusted to a faster speed when the diaphragm is opened wider, or the speed of shutter is lowered when the aperture of the diaphragm is smaller. This demonstrates that the aperture of the diaphragm must be small when attempting to accommodate sufficient DOF. However, this leads to a slower shutter and causes the problem of camera shock. One solution for this situation is to use a tripod to support the camera. However, as tripod is of substantial weight, it is not a perfect portable device, especially whilst traveling. Another solution is to use the film with a higher ISO or to increase the sensitivity of electronic light sensitive device to a higher setting. This will elevate the shutter speed. However, the high ISO films have greater particles and lower resolutions, which are evident after enlargement. The dpi of a high ISO film is also smaller than the lower ISO film. For digital cameras, increasing sensitivity of light sensitive device adversely results in enhancement of noise, the elimination of which depends hugely upon the software and firmware performance of the camera itself, or by the graphics editing software. If these elements or softwares are ineffective, the picture quality will be poor. Therefore, this is not an ideal solution either.
Certainly, another solution is to increase the amount of light projected on the object. Flash light is usually employed to illuminate the object to allow greater reflection of light for the light-sensitive element to detect. However, it is mostly in or above the camera body regardless of whether it is internal or external. Although it is appropriate for ordinary use, in the case of close-up photography, the problem of lens blocking the light remains.
In light of this necessity of providing the object with sufficient light, the conventional approach is to place a close-up flash in front of the lens. However, it is usually designed for professional purpose. An ordinary consumer is generally not able to manage the volume, weight or price. In addition, although most cameras are capable of close-up photography function, it is somewhat limited. If a larger image of the object is required, an additional close-up photography lens has to be installed. The installed close-up photography lens will make it even more difficult to install a close-up flash.
Furthermore, not all digital cameras have the close-up photography function. Although it is possible to install an extra close-up photography lens on digital cameras in the market, the problem of insufficient light on the object will be encountered when it comes to performing the close-up photography. There is also difficulty in arranging the close-up photography flash and lens.
Lastly, the flash light only works when shooting. Unless the user has ample experiences, it is hard to imagine the photo taken. Therefore, it is an important task to solve the drawbacks of the close-up photography associated with digital cameras.